An introduction to the amplification circuit of analog electronic technology and the performance of each configuration

In analog electronic technology, we need to master the basic structure of the basic components and the characterization of the main parameters from the contact of simple diodes to transistors (BJT) to integrated circuits. I will not elaborate on the internal components of diodes and transistors (BJT), which can be described in more detail by reference to the relevant information.

In the transistor, a very important value is the static work point Q, the static operating point Q for the transistor distortion problem has a great impact, so in the design, you must do a good job Q point settings, otherwise there will be saturation distortion or cut-off distortion. Another way to analyze the amplification circuit is the small signal model analysis method. This method is mainly to the transistor's correlation circuit equivalent to two-port network, using the H parameter to analyze the basic characteristics of the port at both ends. It should be noted that both ends of the port in the equivalent process, the current source and voltage source of the controlled situation need to understand clearly. Then the basic method and basic steps of the basic amplification circuit are analyzed by using H parameter.

(1) The small signal equivalent circuit of the amplifying circuit is drawn.

(2) Estimating Rbe.

(3) Seeking voltage gain Av.

(4) Calculate input resistance ri.

(5) Calculate the output resistance ro.

After learning the most basic common emitter amplification circuit, we can learn the corresponding common base and the common collector amplification circuit, and their analysis methods can use the basic small signal equivalent model, using the H parameter to analyze. Among them, they have their own different uses.

The common emitter circuit is mainly used in the intermediate stage of multilevel amplification circuit.

The common collector circuit is mainly used for input stage, intermediate stage and output stage.

The common base stage circuit is mainly used for high frequency or wideband circuits.